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John - I've been messing around with it on some scraps and so far I do *really* like the way it lays down - I dont know enough about it though to know if it would be okay to use as the main bonder on all the joints of the pipe. It sounds like you have used this stuff a lot and have a good familiarity with it, you think I would be okay to use it on basically the entire pipe? I know its got a lower tensile strength than regular er70s2 filler but its also softer - so I was *thinking* it'd be okay, but didn't know for sure?

2 stroke thinker

well, for a first time pipe builder...I assume..(tig welding) I think you did an incredible job being that you were handed like 200 pieces of straight metal that you had to form and weld to make it fit into the frame!

Nice job!

Nice "Big Bodied Pipe" should run nice!....Oh BTW. What software did you use to design your pipe and is it for your rotax-250r build?
Kinda hard to see with that big monster pipe blocking the motor!

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Thanks! I ended up using "Two Stroke Pipe Wizard" by www.buildandclick.com which looks kind of cheesy at first glance but I had talked to some people that had used it with good success. It is for the Rotax-250R build. I'm getting into the home stretch with it finally. I have a lot more to do, but there is some light at the end of the tunnel now at least

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I am a bit surprised how large it came out myself - I set target RPM for max Hp to be about 7500 which I thought for a 400cc single wasn't terribly out of line. It shouldn't be an all drag pipe from what I plugged in...we'll find out I suppose

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Bravo! I have built pipes using both methods, hand rolled cones and hydroforming. I have a woodward fab slip roll with the 1 1/4" roll diameter. It only has a 12" roll length but it works for all but the largest of mainbodies.

Hydroforming was accomplished on 18 gauge sheet steel cut with a woodward fab throatless rotary shear and tigged together all along to form a steel "balloon". An industrial pressure washer was hooked up and the balloon inflated. There are a few odd things about hydroforming. Any sharp changes in the shape of the pipe can result in a wrinkle. It's best to make a very smooth gradual transition into the shape. When you have a shape that "grows" in cross section like a pipe does, the outside bends more than the inside so the pipe actually "closes" up a bit during inflation. The exact amount varies based on the angle of divergent section of the pipe but they all shrink.

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Rule #1: There’s more or less a set amount of power available for you to manipulate. If you port for high RPM power then your low/mid-range power will suffer. You are robbing Peter to pay Paul.
Rule #2: You are pretty much stuck with the porting arrangement the factory put in your cylinder. If...

Essentials to know first:
The peak power and length of powerband are mostly controlled by the design of the expansion chamber.
The engine porting determines whether high RPM or mid range RPM is where the engine harmonizes the most for the most power (relatively speaking).
The carb size favors...

My Engine Oil Summary
Fully mineral oil (petroleum oil) protects OK but only when using a generous amount of it. But using a high amount of it dirties the engine and the exhaust pipe quickly with carbon. This is definitely not good for engines with exhaust valves. But if you are after high...

Here's my assessment of the formulas proposed by Gordon Jennings way back in the early 70's. They were just beginning to investigate back then and so were starting from scratch.
Jennings main shortcomings;
0. He assumes the same temperature and sound wave speed inside all pipes.
1. Because of...